The field of this invention is heating assemblies for transferring heat to instruments.
The use of thermostatically controlled electric resistance-type heaters is known in the art for accomplishing various heating objectives such as those disclosed in U.S. Pat. Nos. 1,627,564; 1,797,712; 2,606,271; 2,813,961; 2,906,849; 3,036,190; 3,146,977; 3,335,459; 3,349,722; and 3,412,231.
More specifically, the patent of E. L. Volling, U.S. Pat. No. 3,538,302, discloses threaded heat assemblies which are positioned in bolt openings of an instrument housing to thermostatically control the temperature of the instrument. Since the heating assemblies replace bolts in bolt openings of the instrument housing, the integrity of the instrument is disturbed and users are frequently concerned that such usage will cause damage to or malfunctioning of the instrument. Such arrangement further results in the disadvantage of producing localized heat within the instrument housing. In some instances, with the Volling device, because the localized heat generation is in proximity to sensitive portions of the instrument, an output signal is produced that is not representative of the actual conditions detected by the instrument.